The proposed research will result in improved ability to relate ionic flux measurements to molecular structure of those membrane proteins that give rise to ionic permeability in biological membranes. The long-term goal is to contribute to making studies of membrane ion permeation an area of molecular biology. The specific aim, which will contribute to that goal is to develop the Brownian dynamic method for simulating ion fluxes in membrane channels. This method is inherently more powerful in correlating ionic flux to channel structure than either Eyring rate theory or bulk electrodiffusion theory, the currently widely utilized means of calculating ionic fluxes. It appears that Brownian dynamics flux calculations can be coupled to molecular dynamic conformational energy calculations to provide a theory that can predict fluxes given molecular structure. This theory might ultimately be used to "design" membrane channel proteins. Presently there is developing much interest on the part of drug companies in utilizing molecular dynamics in the design of biologically active molecules. The proposed work will help make this concept applicable to membrane proteins and thus move forward the day when one can genetically engineer membrane channel proteins with desirable ion permeability properties.